Golf is a sport that is enjoyed throughout the world. Golfers use a variety of golf clubs to hit a ball into a hole or pin. Depending upon the individual course or hole, the golfer may be required to hit the ball several hundred yards. The golfer will first use a wood-type golf club, then a iron club, and finally a putter once he or she is on the green.
Slight mistakes on the part of the golfer can result in the ball being hit out of play, or simply not in the desired direction. Golf balls are small, hard balls, designed to maximize travel distance. The drawback to hard golf balls is that they impart very little “feel” to the golfer when he strikes the ball with the golf club. The “feel” that a golfer senses when he strikes the ball imparts information that, in part, enables the golfer to improve his or her golfing skill. Golf club “feel” is a combination of several factors, some of which are the vibration that travels up the golf club shaft from the golf club head and the sound that is made when the golf club hits the golf ball. The “feel” transmits important information to the golfer including whether the golf ball was struck with the correct area of the golf club head.
When a golf ball is struck with the wrong part of the golf club head, the golf ball generally does not travel in the direction desired. Preferably, the ball-striking face of the golf club will have a large “sweet spot,” which will direct the ball in the desired direction. To achieve this golf club head characteristic, golf clubs have been constructed with high polar moments of inertia.
The polar moment of inertia of an object is a measure of how easily the object rotates about an axis of rotation. Objects with a large polar moment of inertia will be harder to rotate than objects with a small polar moment of inertia. The force of a golf ball striking a golf club head will create a torque about the golf club shaft. A golf club head constructed with a large polar moment of inertia will resist the torque force more than a golf club head having a small polar moment of inertia. The resistance to the torque force results in the golf ball going in the desired direction even when the golf ball is struck outside the “sweet spot.”
A high polar moment of inertia is achieved by adjusting the weight distribution across the club head. Various weighting techniques have been employed to increase the polar moment of inertia, thereby increasing the “sweet spot.” Such techniques often involve either perimeter weighting in which the weight is distributed to the perimeter areas of the club away from the center of the club head, or heel-toe weighting in which materials having different densities are used in the heel, toe and center portions of the club head in order to distribute more weight in the heel and toe of the golf club. However, golf clubs that have a high polar moment of inertia generally have little or no “feel.”
Therefore, there exists a need for a golf club head that combines a high polar moment of inertia with an optimum “feel” that imparts information and confidence to a golfer.